1. Field of the Invention
The invention relates to a semiconductor film formation device and, particularly, to a semiconductor film formation device that is provided with a temperature control means to control the internal temperature of reaction vessel to offer a good evenness in film thickness and composition ratio.
2. Description of the Related Art
Conventionally, the CVD (chemical vapor deposition) method is used to grow a semiconductor film on the surface of a wafer. In the CVD method, source gases supplied into a reaction vessel react with each other on the surface of a substrate disposed in the reaction vessel and its reacted product is deposited on the substrate while being grown as a semiconductor film. It is desired that the semiconductor film thus produced has a good evenness in thickness, composition and impurity distribution. Such evenness is influenced by conditions of gas flow and temperature distribution in the reaction vessel. Thus, it is important to finely control these conditions to have a semiconductor film with good evenness.
Japanese patent application laid-open No. 4-132213 discloses a semiconductor film formation device that the internal temperature distribution of reaction vessel is controlled by providing pipes for coolant in the wall of reaction vessel and by separately setting the temperature or flow rate of coolant to be supplied through the pipes.
However, the conventional semiconductor film formation device has problems as below.
The device is complicated in its structure since it needs to provide pipes for coolant in the wall of reaction vessel. Therefore, the manufacturing cost must be increased.
Further, the device is complicated in its operation since it needs to separately set the temperature or flow rate of coolant to be supplied through the pipes. Therefore, the operating or maintenance cost must be increased.